REMARKS
The 1852 Ft. Snelling climatological record consists of: four daily fixed time readings taken from the station's "detached" thermometer; daily precipitation values; four daily fixed time sky cover observations; four daily fixed time observations of wind "force" and wind direction; four daily barometric readings; and four daily readings from the station's "attached" thermometer (i.e. from an indoor thermometer used to adjust barometric readings for the effects of temperature on the station's mercury barometer) . Temperature, sky cover, wind direction/force and barometric observations were taken at or about local sunrise, at or about 0900 hours, at or about 1500 hours and at or about 2100 hours local solar time. Although extant records give no explicit indication of the time at which 1852 precipitation observations were taken, contextual evidence suggests either a 2100-2100 schedule and/or an early morning (probably "sunrise") schedule (which, in at least in some instances, may have entailed "shifting" of precipitation values from the date on which the observation was actually made to the day immediately preceding).
So far as can be determined, 1852 Ft. Snelling temperature readings were taken from an instrument manufactured by George Tagliabue, New York City, and precipitation observations were taken from a DeWitt rain gauge (which was probably mounted on a pole or post on the fort's parade ground). With the possible exception of some mid-summer readings, fixed time temperatures recorded by Ft. Snelling observers during 1852 appear to be consistent with "normal" diurnal patterns (indicating that the station thermometer was, for the most part, located/sheltered as necessary to protect it from the early morning, mid-morning and/or afternoon sun).
All 1852 wind force values are expressed in terms of a numeric wind force value selected by fort observers after visually noting the effect of wind on flags, trees, signs and other easily movable objects . The degree of cloudiness was similarly quantified, using a scale of zero (complete overcast) to ten (a totally cloudless sky) . However, discontinuing a practice first introduced in 1846 (and temporarily re-introduced in 1851), Fort observers did not note the number of "fair" and "cloudy" days during each month of 1852.
Unlike the 1852 daily sky cover record (which includes a complete set of daily entries), the 1852 force of wind record is occasionally incomplete: several air movement records include wind direction entries UNACCOMPANIED by corresponding numeric wind speed indicators. Extant records give no explanation for these lapses: perhaps the missing entries indicate a force of wind value of more than zero but less than one or, alternatively, that fort personnel, for whatever reason, were unwilling or unable to expend the time and effort required to take consistent wind speed observations. As a result, several 1852 monthly average force of wind values are based on incomplete/partial data.
Like corresponding records from the years immediately preceding, the 1852 Ft. Snelling record appears to significantly understate the number of days with precipitation and/or measurable precipitation. This suggests that -- following the example of their predecessors -- Fort observers did not routinely/consistently measure and/or record small precipitation events, sometimes either ignoring less significant deposits of rain or snow (or. alternatively, using terms such as "inappreciable", "unmeasurable" or "slight" to denote small, but perhaps otherwise measurable, amounts of precipitation). This tendency is particularly evident in records for the winter months of year: St. Paul newspaper accounts -- together with contextual evidence from the 1852 record itself -- suggest, in fact, that Fort observers, for whatever reason, failed to measure or record (or even note) a significant portion of the precipitation which fell during the winter months (and, to a lesser extent, probably the summer months as well).
Although the 1852 Fort Snelling record includes daily liquid/melted precipitation values and a record of the TYPE of precipitation observed, it contains NO QUANTITATIVE snowfall values (whether of fresh snowfall or accumulated snow cover). Therefore, unless otherwise noted, snowfall values in the foregoing compilation are values obtained from monthly meteorological reports prepared by St. Paul observers and published in 1852 St. Paul newspapers and/or inferred from anecdotal journalistic accounts of 1852 winter weather.
In addition to outdoor temperature, sky cover, precipitation and air movement data, the 1852 Ft. Snelling record (as noted previously) includes four daily readings taken from the station's mercury barometer and from the "attached" thermometer (readings which, also as noted above, were probably used to correct air pressure readings for the effects of temperature on the mercury in the station barometer). So far as can be determined, 1852 barometric values are station pressures (i.e. readings which have not been adjusted to compensate for elevation above mean sea level).
Analysis of the 1852 Ft. Snelling temperature record suggests that some summer temperature values (particularly during July and August) may have been compromised by improper instrument exposure and/or erratic observational schedules. Specifically, some fixed time temperature readings taken during the warm months of 1852 suggest an inordinate "compression" of daily readings taken at 0900, 1500 and, to a lesser extent, 2100 hours. This suggests, of course, that the station thermometer may sometimes have been exposed to the mid-morning summer sun and/or that observations were sometimes taken at times significantly different than the times indicated in the official record .
The foregoing 1852 climatological record includes both unadjusted (UNADJ) and adjusted (ADJ) mean temperature values. Unadjusted values are the simple mean of fixed time readings taken daily at sunrise, 0900, 1500 and 2100. Adjusted averages are from Charles J. Fisk's 1984 "Reconstruction of Daily 1820-1872 Minneapolis-St. Paul Temperature Observations". These values were obtained by averaging statistically derived estimates of the daily maxima and minima which would have been recorded had the Ft. Snelling station been equipped with self-registering thermometers read and re-set at midnight . The foregoing 1852 temperature record also includes both the monthly and annual extremes (lowest daily maximum, etc.) estimated by Fisk and the monthly extremes actually recorded by fort observers. All 1852 temperature distributions (e.g. days 90 F or higher, 32 F or lower, etc.) are based on Fisk's estimates of daily maxima and minima.
All foregoing monthly mean cloudiness and force of wind values are the simple average of the station's four daily numeric sky cover and wind speed entries. The foregoing prevailing wind values are based on daily entries indicating the direction of the wind at sunrise/0900/1500/2100: prevailing/predominate winds are those most frequently observed/recorded during any given month.
In addition to the Ft. Snelling record, the 1852 climatological record includes narrative summaries of January, February, March and April 1852 weather conditions prepared by a St. Paul observer identified only as "M..y" and published in 1852 St. Paul newspapers. These records are based on fixed time readings taken daily at 0700, 1200 and 2100 hours. The exact location of "M..y's" station is unknown.
Severe mid-January cold wave: Ft. Snelling readings of -32 F, -30 F and -25 F at sunrise, 0900 and 1500, respectively, on 19 January. Readings as low as -34 F noted at "exposed locations" in St. Paul on that date. Low temperatures (Ft. Snelling sunrise reading of -25 F) on 18 January accompanied by a "perfect gale" which blew throughout the day. Late January thaw which, according to "M...y", melted "what little snow there was on the ground, leaving mud in its place..". "Bright and warm" sun with temperature of 45 F noted in St. Paul on 28 January. Sunrise reading of 33 F at Ft. Snelling on 30 January. "Driving snowstorm from the northwest" noted on 31 January. Warm February with record warmth early in the month: afternoon readings of 55 F and 57 F at Ft. Snelling on 5, 9 February, respectively. Sunrise readings of 36 F and 38 F on 6, 10 February, respectively. St. Paul newspaper account described early February weather as "being as mild as April...the mud is drying up in our streets...". Severe windstorm on 24 February: Ramsey county courthouse in St. Paul "partially unroofed". Rain on 5, 23 February. St. Paul newspapers noted snowstorm with four inches of light snow on 26-28 February. Cold late February. Cold mid-March: Ft. Snelling readings of -4 F, -2 F and 4 F at sunrise, 0900 and 1500, respectively on 18 March; -8 F, -5 F and -2 F at sunrise, 0900 and 1500, respectively, on 19 March. Thunderstorm with heavy rain and snow on 8 March: heavy rains on 11, 14 March. "Driving snowstorm" noted on 16-17 March. Very cold during the first days of April: Ft. Snelling readings of 4 F, 8 F and 24 F at sunrise, 0900 and 1500, respectively, on 1 April. Reading of 6 F at "M...y's" St. Paul station at 0800 on 1 April. Heavy fall of snow on 25 April. Excessive rains on 12-16 May: 3.7 inches recorded at Ft. Snelling, local flooding reported in Stillwater and some rain damage reported in St. Paul. High river levels also noted in mid-May. Very cold, 16-20 May. Sunrise readings in the 30's F at Ft. Snelling each day during that period. Afternoon readings of 40 F and 42 F on 16, 17 May, respectively. Early vegetation destroyed by frost on 18-19 May. Sunny and warm late May. Fluctuating temperatures and near record drought during June. Reading of 96 F at 1500 on 1 June. Sunrise readings of 34 F and 38 F on 9, 24 June, respectively. Damaging winds noted in St. Paul on 6 June. St. Paul newspaper account [1 July] noted that "there never has been a time before when we have experienced anything like such a drought in Minnesota as now...". Warm , foggy July. Several very cool mornings during July: sunrise readings of 46 F and 45 F at Ft. Snelling on 1, 10 July, respectively. Damaging winds accompanied heavy thunderstorms on 5, 8 July. Warm, sunny and very dry August. St. Paul newspaper [19 August] noted "hot and Illinois like weather...many people down with dysentery...vegetation suffers, together with animal life...". Very low river levels noted during August. Very cool and dry September. Sunrise readings of 38 F, 37 F, 33 F, 30 F, 37 F, 34 F, 35 F and 33 F at Ft. Snelling on 12, 13, 14, 15, 16, 19, 21, 22 September, respectively. Afternoon reading of 48 F on 15 September. Frost during the night of 13-14 September, "destroying all vegetation". St. Paul newspaper account of the event stated "the first frost of the season visited us on the night of the 13th...our people are praying for rain to raise the river and lower freights...we had a little bit of rainstorm on Monday [20 September] but next morning opened...clear and dry [no precipitation was recorded at Ft. Snelling on 20 September]..". Rain with strong winds on 30 September. Very warm, sunny and dry October: afternoon reading of 83 F at Ft. Snelling on 17 October. St. Paul newspaper account indicated that late September and early October rains were sufficient to raise the Mississippi river about eight inches [probably indication of heavy upstream rains: so far as can be determined, only scant to moderate rainfall occurred in the Ft. Snelling-St. Paul area during this period]. Prairie fires noted on 22 October: newspaper accounts indicate extensive damage from fires in areas south of what is now the Twin Cities. Cold November: sunrise reading of zero F at Ft. Snelling on 17 November. Newspaper accounts indicate that November was a very snowy month: eighteen hour snowfall reported on 10-11 November with snow depth of six to eight inches in St. Paul on 13 November. "All day" snowfall noted on 21 November: accumulations of three to four inches indicated. More snow noted on 23 November with "a warm south wind and some rain". Snow cover of twelve inches noted on 27 November. Thawing conditions with rain showers during the first days of December. Very cold late December: Ft. Snelling readings of -24 F and -10 F at sunrise and 1500 hours, respectively, on 21 December. Reading of -19 F at 1500 on 20 December. St. Paul newspaper account [written 1 January 1853] stated that "we believe there were not three consecutive days during the past month that did not bring a snowstorm...the snow is now between two and three feet deep in adjacent woods...the storm on Monday [27 December] was the most severe that we have ever had...it lasted some sixteen hours and was accompanied by wind which drifted it to nearly the height of fences about town...". Another account of the same event indicated that "snow has fallen...to a depth of probably one foot...it lies flat and doesn't curl in the breeze...snowstorms have visited us to a greater extent thus far than during the whole of the past two winters..our streets and roads are filled...on Tuesday [a probable reference to the 21 December cold wave] the thermometer stood at 28 degrees below zero...".